Two French infrastructure investors have reportedly emerged as potential bidders for the UK taxpayer’s 40% stake in Eurostar.

Paris-based Antin Infrastructure Partners and private equity company Ardian are contemplating bids for the slice of the train operator, according to the Sunday Times.

The government put the stake up for sale last December as part of a plan to privatise £10 billion of state assets.

Investment bank UBS has been appointed to sell the Eurostar stake, reportedly worth about £300 million, and is due to ask for expressions of interest. The French state train company SNCF owns 55% of Eurostar and Belgium’s SNCB holds 5%.

Eurostar reported flat pre-tax profits of £56.3 million last year on revenues 7% higher at £882.2 million, helped by an increase in business travellers. It paid £18.6 million in dividends last year to its British, French and Belgian state owners as more than 10 million passengers travelled on its trains for the first time.

The position of the high-speed rail service, established in 1994, has been reinforced by repeated delays to Deutsche Bahn’s plans to break its monopoly by launching services between London and Frankfurt.

Eurostar has plans for a London to Amsterdam service from December 2016 and has ordered new express trains, some of which will come into service next year. It plans to unveil the first of the 10 new trains in London next month as part of a £700 million investment in rolling stock.

Eurostar is also bidding, with France’s Keolis, to run the UK’s East Coast main line route. It is up against First Group and a joint bid from Virgin and Stagecoach. The Department for Transport has pledged to select the winning bidder next month, despite fierce opposition from Labour, which wants the line to remain in public hands.

SNCF reportedly has a pre-emption right on any change in ownership at Eurostar, but it is not thought to be keen on beefing up its stake.

Antin, which has an office in London, is part of a consortium that is selling Porterbrook, owner of a third of Britain’s trains. Ardian manages $50 billion of assets and backs the Eat sandwich chain. It also has stakes in Luton airport and the Vinci car parks business.